Soil Biology & Biochemistry最新文献

{"title":"Response of wheat to arbuscular mycorrhizal fungi inoculation and biochar application: Implications for soil carbon sequestration","authors":"A.R.G. Mason ,&nbsp;A.J. Lowe ,&nbsp;C. Brien ,&nbsp;N. Jewell ,&nbsp;T.R. Cavagnaro ,&nbsp;M.J. Salomon","doi":"10.1016/j.soilbio.2024.109611","DOIUrl":"10.1016/j.soilbio.2024.109611","url":null,"abstract":"<div><div>The sequestration of atmospheric CO₂ in soil is suggested as an effective climate change mitigation strategy. Biochar application shows promise in this regard, while the role of fungi in soil carbon cycling and sequestration is also under investigation. Using a novel high-throughput plant phenomics approach, we explore the impact of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on wheat growth and soil carbon, guided by one of the leading global carbon credit schemes. Wheat was successfully colonised by AMF, achieving an average root length colonisation of 35.9%. We uncover an indirect fungal-mediated pathway to soil carbon sequestration, with mycorrhizal plants generating more biomass across all soil treatments without yield penalties, suggesting colonised plants deliver more plant derived carbon to the soil, potentially leading to long-term soil carbon gains. Conversely, fungal-driven carbon loss occurred, significantly reducing soil carbon accumulation in unamended soil, but not in biochar-amended soil, suggesting that biochar moderates fungal activity and positively impacts the soil carbon balance. While both biochar and AMF enhance plant growth, their direct effects on soil carbon are complex. Although biochar did not significantly increase soil carbon stocks beyond its own contribution, its ability to regulate fungal activity could play an important role in influencing soil carbon sequestration.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109611"},"PeriodicalIF":9.8,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of climate warming and exogenous nitrogen input on soil N2O emissions from mangroves","authors":"Weimin Song ,&nbsp;Yan Zhao ,&nbsp;Jian Zhou ,&nbsp;Jianxiang Feng ,&nbsp;Zhonglei Wang ,&nbsp;Guangxuan Han ,&nbsp;Elise Pendall ,&nbsp;Guanghui Lin","doi":"10.1016/j.soilbio.2024.109607","DOIUrl":"10.1016/j.soilbio.2024.109607","url":null,"abstract":"<div><div>The paucity of studies on nitrous oxide (N₂O) dynamics with rising temperatures and nitrogen (N)-based eutrophication makes it challenging to evaluate the role of mangroves in mitigating climate change. Here, a 3-year mesocosm experiment was conducted to investigate the effects of climate warming (+3 °C) and excessive N input (25 mg N L⁻¹) on soil N₂O emissions from two mangroves (<em>Avicennia marina</em> and <em>Bruguiera gymnorrhiza</em>). We found that warming and N input alone significantly increased soil N₂O emissions from both mangroves, while the interactive effects of warming and N input on soil N₂O emissions were affected by mangrove species. Warming mitigated the positive effect of N input on soil N₂O emissions from <em>A</em>. <em>marina</em>; and amplified the effect of N input on soil N₂O emissions from <em>B. gymnorrhiza</em>, suggesting that the response of soil N₂O emissions to these global change factors is species-dependent. Stable isotopic signature analysis revealed that both warming and N input significantly increased the relative contribution of nitrification to N₂O emissions from <em>A</em>. <em>marina</em>; whereas N input, rather than warming, significantly changed the relative contribution of nitrification in <em>B. gymnorrhiza</em>. This could be attributed to the differential changes in soil environmental conditions, plant growth and the microbial structure of the two mangroves. Overall, this study highlights the role of mangrove species in modifying the effects of warming and N input on soil N₂O emissions, which should be considered when accurately projecting N₂O emissions from mangroves. Furthermore, considering the low N₂O emissions from background sediments and the common N limitation across mangroves, our findings suggest that climate warming and exogenous N input may lead to a surge of N₂O emissions from mangroves, especially those that are seriously affected by human activities.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109607"},"PeriodicalIF":9.8,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering the active bacteria involving glucose-triggered priming effect in soils with gradient N inputs","authors":"Shengxian Chen ,&nbsp;Junjie Guo ,&nbsp;Ruijia Guo ,&nbsp;Baiqing Huang ,&nbsp;Jian Huang ,&nbsp;Min Wang ,&nbsp;Qirong Shen ,&nbsp;Ning Ling ,&nbsp;Shiwei Guo","doi":"10.1016/j.soilbio.2024.109612","DOIUrl":"10.1016/j.soilbio.2024.109612","url":null,"abstract":"<div><div>The soil priming effect, which refers to the alteration of soil organic matter (SOM) decomposition due to labile carbon (C) inputs, is widely acknowledged for its impact on C storage in terrestrial ecosystems. However, the impact of chronic nitrogen (N) fertilizer on soil priming effect, particularly in agroecological systems, remains unclear. Here, we utilized soils subjected to varying levels of N fertilization (0, 140, 280, 470, and 660 kg N ha⁻¹ y⁻¹), which were collected from a long-term experimental site. Enzyme activity related to C, N, and phosphorus (P) acquisition was measured using the fluorometric method. Additionally, DNA-based stable isotope probing with ¹³C-labeled glucose was conducted to explore the role of active bacterial communities (16S rRNA gene analysis) on the priming effect in soils with different N fertilization histories. Glucose addition enhanced the decomposition of native SOM and induced positive priming effects in all soils, which were amplified by the historical N application level. Activity of C-related enzymes essential for soil C decomposition increased following glucose addition, which was positively correlated with the soil priming effect. Active bacterial taxa, primarily <em>Firmicutes</em>, <em>Actinobacteria</em>, and <em>Proteobacteria</em>, were capable of assimilating exogenous glucose-C or native SOM-C. Notably, bacteria assimilating glucose exhibited higher abundance-weighted average ribosomal RNA gene operon copy number than those assimilating SOM, indicating the role of r-strategists in accelerating SOC turnover and increasing C loss. These findings highlight the role of active microbial community attributes on the soil priming effects. This study provides new insights into the intricate processes of C transformation in soils subjected to long-term N management in agroecosystems.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109612"},"PeriodicalIF":9.8,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental evidence that poor soil phosphorus (P) solubility typical of drylands due to calcium co-precipitation favors autonomous plant P acquisition over collaboration with mycorrhizal fungi","authors":"Kurt O. Reinhart ,&nbsp;Lance T. Vermeire ,&nbsp;Chad J. Penn ,&nbsp;Ylva Lekberg","doi":"10.1016/j.soilbio.2024.109605","DOIUrl":"10.1016/j.soilbio.2024.109605","url":null,"abstract":"<div><div>Calcareous dryland soils are rich in precipitated phosphate and represent &gt;30% of Earth's land, yet the relative importance of phosphorus-acquisition strategies (P_AS) among plant species in these systems is not well known. No experiment has investigated potential interactions between varying amounts of added calcium carbonate (CaCO₃) and arbuscular mycorrhizal fungi (AMF) on plant performance and P_AS which could test for potential mechanisms without the limitations of <em>in-situ</em> comparisons along natural gradients. To fill this knowledge gap, we conducted an experiment with CaCO₃ addition, AMF inoculation, and three invasive and five native grassland plants. We expected an increase in soil [CaCO₃] of an alkaline subsoil to 1) reduce soil-available phosphorus (P), 2) reduce plant biomass and P uptake, and 3) shift P_AS toward increased root mining as Ca-bound P increases. The largest CaCO₃ addition reduced available P by as much as 57%. On average, the largest addition of CaCO₃ reduced total biomass of plants by 19% and plant uptake of P by 15%. The P_AS seemed to have changed, and CaCO₃ additions tended to increase an indicator of root exudation (shoot [Mn]) to mobilize Ca-bound P, suggesting plasticity for some inducible root mining, especially <em>Artemisia frigida</em> and <em>Poa secunda</em>. However, CaCO₃ and plant species interacted to affect shoot [Mn]. The invasive grass <em>Bromus tectorum</em> was superior at acquiring P (&gt; P uptake, &gt; shoot [Mn]) and thus tolerating low soluble P conditions. Rarely did AMF and CaCO₃ interact to affect plant biomass. When they did, mycorrhizal responsiveness did not increase where P was less available, suggesting AMF become less beneficial upon P and Ca coprecipitation. In dryland soils with less soluble P, plants are thus likely to rely more on root mining P_AS than mycorrhizal scavenging, except for the invasive forb <em>Euphorbia esula</em> that always benefitted from AMF inoculation.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109605"},"PeriodicalIF":9.8,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial-temporal patterns of foliar and bulk soil 15N isotopic signatures across a heterogeneous landscape: Linkages to soil N status, nitrate leaching, and N2O fluxes","authors":"Elizabeth Gachibu Wangari ,&nbsp;Ricky Mwangada Mwanake ,&nbsp;Tobias Houska ,&nbsp;David Kraus ,&nbsp;Hanna-Marie Kikowatz ,&nbsp;Benjamin Wolf ,&nbsp;Gretchen M. Gettel ,&nbsp;Lutz Breuer ,&nbsp;Per Ambus ,&nbsp;Ralf Kiese ,&nbsp;Klaus Butterbach-Bahl","doi":"10.1016/j.soilbio.2024.109609","DOIUrl":"10.1016/j.soilbio.2024.109609","url":null,"abstract":"<div><div>The natural abundance of plant and bulk soil ¹⁵N isotopic signatures provides valuable insights into the magnitude of nitrogen cycling and loss processes within terrestrial ecosystems. However, ¹⁵N isotopic signatures are highly variable in space due to natural and anthropogenic factors affecting N cycling processes and losses. To date, most studies on foliar and bulk soil ¹⁵N isotopic signatures have focused on N-limited forest ecosystems at relatively large spatial scales, while similar studies in N-enriched ecosystems at finer spatial scales are lacking. To address this gap and evaluate links between soil ¹⁵N isotopic signatures and ecosystem N cycling and loss processes (plant N uptake, N leaching, and gaseous loss), this study quantified foliar and bulk soil ¹⁵N isotopic signatures, soil physicochemical parameters, gaseous (N₂O), and hydrological (NO₃) N losses at 80 sites distributed across a heterogeneous landscape (∼5.8 km²). To account for the spatial-temporal heterogeneity, the measurements were performed in four campaigns (March, June, September 2022, and March 2023) at sites that considered different land uses, soil types, and topography. Results indicated that foliar and bulk soil ¹⁵N isotopic signatures were significantly (P &lt; 0.05) more enriched in arable and grassland ecosystems than forests, suggesting a more open N cycle with significant N cycling and losses due to higher N inputs from fertilizers. Similar to soil inorganic N, N₂O fluxes, and NO₃ leaching rates, landscape-scale foliar and soil ¹⁵N isotopic signatures varied widely spatially, particularly at grassland and arable land (−3 to 9.0‰), with bivariate and multivariate analyses also showing significant relationships between landscape-scale soil ¹⁵N isotopic signatures and the aforementioned parameters (r²: 0.29 to 0.82). Based on these relationships, our findings suggested that foliar and bulk ¹⁵N isotopic signatures may capture fine-scale areas with persistently high and low environmental N losses (N₂O fluxes and NO₃ leaching) within a heterogeneous landscape.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109609"},"PeriodicalIF":9.8,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of earthworm species on organic matter transformations and soil microbial communities are only partially related to their bioturbation activity","authors":"Luna Vion-Guibert ,&nbsp;Yvan Capowiez ,&nbsp;Gonzague Alavoine ,&nbsp;Ludovic Besaury ,&nbsp;Olivier Delfosse ,&nbsp;Mickaël Hedde ,&nbsp;Claire Marsden ,&nbsp;Gwenaëlle Lashermes","doi":"10.1016/j.soilbio.2024.109606","DOIUrl":"10.1016/j.soilbio.2024.109606","url":null,"abstract":"<div><div>Earthworms are pivotal in shaping soil ecological processes through their bioturbation activity and organic matter consumption. Earthworm species are known to have different impacts on soil structure, but only a small number of species have been studied so far, and few studies have examined how earthworms simultaneously affect soil functions. Here, we measured the impact of different earthworm species on soil structure (bioturbation function), carbon (C) and nitrogen (N) dynamics and the microbial community (organic matter transformation function), while exploring the links between these functions, across distinct soil compartments (surface casts, below-ground drilosphere, and bulk soil). Six earthworm species <em>(Lumbricus terrestris</em>, <em>Allolobophora chlorotica</em>, <em>Octolasion cyaneum, Octodrilus complanatus</em>, <em>Aporrectodea caliginosa meridionalis</em> and <em>Microscolex dubius</em>) of different ecological categories and functional groups were incubated in soil cores with soil and alfalfa litter for 6 weeks. Our results on the bioturbation function illustrated a great diversity of behaviors and confirmed the relevance of a functional classification based on bioturbation metrics. The main microbial hotspots were surface casts, whose characteristics allowed to distinguish two groups of species. <em>Octod. complanatus, L. terrestris</em> and <em>M. dubius</em> induced high humidity (respectively, +57, +48, +74%), high C (respectively, 19.9, 24.8, 33.2 g kg⁻¹ dry soil) and N (respectively, 2, 2.3, 3.2 g kg⁻¹ dry soil) content and microbial community selection, promoting C and N mineralization. The three other species had a lower impact. The below-ground drilosphere only showed specific characteristics in the case of <em>L. terrestris</em>. The effects of the studied species on the organic matter transformation function did not align with their bioturbation activities nor with their ecological category. These findings show that the contribution of earthworms to C and N turnover is only partially dependent on their bioturbation effects and suggest the usefulness of developing distinct functional groups based on the specific soil functions under consideration.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109606"},"PeriodicalIF":9.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transformed biosolids promote ryegrass growth and microbial carbon cycling at the ‘cost’ of soil carbon","authors":"George D. Mercer ,&nbsp;Bede S. Mickan ,&nbsp;Deirdre B. Gleeson ,&nbsp;Megan H. Ryan","doi":"10.1016/j.soilbio.2024.109603","DOIUrl":"10.1016/j.soilbio.2024.109603","url":null,"abstract":"<div><div>Soil carbon supports desirable ecosystem functions for global agricultural productivity and climate resilience objectives. Wastewater biosolids can be transformed into soil amendments that return carbon and nutrients to agricultural systems in stoichiometric ratios that support carbon stabilisation. However, practicable delivery that enhances stable soil carbon and plant yield remains challenging. Soil carbon stability and nutrient availability are mediated partly by microbial community composition and function, which are poorly understood in soils amended with transformed biosolids. We conducted a 56-day study in a temperature-controlled glasshouse, growing perennial ryegrass (<em>Lolium perenne</em>) in pasture soil amended with straw, straw supplemented with nutrients, or transformed biosolids (composted biosolids, dried biosolids or biosolids biochar), all with equal added carbon (3500 kg ha⁻¹). Control soils, with and without supplementary nutrients, were also included. Plant dry mass, soil chemical characteristics, and soil carbon fractions were measured at harvest. 16S rRNA sequencing was used to infer the composition and putative function of rhizosphere bacterial communities. Shoot dry mass increased for composted biosolids (236%) and dried biosolids (559%), but total carbon in rhizosphere soil decreased for composted biosolids (16.3%), dried biosolids (13.3%) and biosolids biochar (12.7%) when compared to unamended soils. Fine-fraction carbon in rhizosphere soil decreased for straw with supplementary nutrients (6.8%), dried biosolids (6.3%) and biosolids biochar (4.6%). Rhizosphere bacterial communities clustered by treatment, with populations correlated with fine-fraction carbon distinct from those populations correlated with shoot and root dry mass. Path analysis linked fine-fraction carbon loss with increased putative carbon cycling genes, driven by available nutrients and plant growth. Transformed biosolids can trigger a microbial response that reallocates nutrients from organic matter to plants, disrupting soil carbon-nutrient stoichiometry and facilitating carbon loss. Understanding the carbon cost of this ecosystem service is fundamental when translating benefits of transformed biosolids to end users.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109603"},"PeriodicalIF":9.8,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142417622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Precipitation and diameter affect wood decomposition both directly and indirectly via deadwood traits and position","authors":"Wanying Yu ,&nbsp;Congwen Wang ,&nbsp;Johannes H.C. Cornelissen ,&nbsp;Xuehua Ye ,&nbsp;Xuejun Yang ,&nbsp;Qingguo Cui ,&nbsp;Zhenying Huang ,&nbsp;Deli Wang ,&nbsp;Guofang Liu","doi":"10.1016/j.soilbio.2024.109604","DOIUrl":"10.1016/j.soilbio.2024.109604","url":null,"abstract":"<div><div>Woody plants are important components of dryland ecosystems. Our understanding of wood decomposition in drylands, an important component of biogeochemical cycling, is poor compared to that in mesic ecosystems. To uncovering the complex interactive effects of the different key drivers, we studied the effects of precipitation, position (aboveground and belowground), wood size and litter quality of plant species (four to five local species and one widespread woody species) on woody litter decomposition rates along a precipitation gradient from 37 to 369 mm, spanning five dryland sites. Wood dry matter content (DMC) was a critical negative predictor of wood decomposition in water-limited ecosystems. Thicker woody litter had lower decomposition rates (<em>k</em> values) directly because of smaller relative surface exposure, and indirectly through higher wood DMC or lower bark mass ratio (bark mass divided by wood mass for a given branch length). Mean annual precipitation (MAP) increased the <em>k</em> values both directly, and indirectly by decreasing the wood DMC and increasing the bark mass ratio due to species turnover. The <em>k</em> values of buried woody litter were mostly two to three times higher than litter on the soil surface, but not different at the extremely arid site. A steeper slope of the relationship between overall woody litter quality (particularly wood DMC) or annual precipitation and <em>k</em> values was observed belowground than aboveground, as related to the higher moisture belowground than aboveground. These findings highlight the complex interactions among climate (precipitation), litter position, size and quality on wood decomposition in drylands, thereby helping to improve our mechanistic understanding of dryland woody litter decomposition. We conclude that wood decomposition at the regional and local scales will influence biogeochemical cycling in drylands under future climate change through both direct effects of moisture and indirect effects of litter quality characteristics.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109604"},"PeriodicalIF":9.8,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Litter mixture effects on nitrogen dynamics during decomposition predominantly vary among biomes but little with litter identity, diversity and soil fauna","authors":"Shixing Zhou ,&nbsp;Olaf Butenschoen ,&nbsp;I. Tanya Handa ,&nbsp;Matty P. Berg ,&nbsp;Brendan McKie ,&nbsp;Congde Huang ,&nbsp;Stephan Hättenschwiler ,&nbsp;Stefan Scheu","doi":"10.1016/j.soilbio.2024.109602","DOIUrl":"10.1016/j.soilbio.2024.109602","url":null,"abstract":"<div><div>Nitrogen (N) is essential for net primary production, with much of the required N in terrestrial ecosystems derived from recycling via litter decomposition. The diversity and identity of plant species and decomposer organisms affect N cycling during litter decomposition, yet the generality and magnitude of these effects remain uncertain. To fill this gap, a decomposition experiment with four leaf litter species that differed widely in initial litter quality was conducted including single species and all possible multispecies mixtures, with and without microarthropods access across a broad latitudinal gradient covering four major forest biomes of the Northern Hemisphere. The results showed that leaf litter N dynamics (both N loss and N immobilization) in single species treatments depended primarily on litter species identity and the local environmental context. We found strong mixture effects, that overall tended to increase N loss and to reduce ¹⁵N transfer. The relative mixture effects on N dynamics differed among forest biomes, but were little affected by the other factors we manipulated. The N loss of individual litter species in mixtures not only depended on litter identity and soil microarthropod access, but also on forest biomes; while ¹⁵N transfer depended strongly on litter mixing, independently of litter species richness or composition of the mixtures. Litter N dynamics were mainly driven by a small subset of litter traits, regardless of species richness and microarthropod access. Overall, our results highlight that litter mixture strongly affects N dynamics during decomposition, with the mixture effects predominantly varying among forest biomes but little with litter identity, diversity and microarthropod access. To improve predictions on how changes in tree species composition and diversity may impact nutrient dynamics in forest ecosystems in face of increasing N deposition, interactions between litter and soil but also within litter mixtures need closer attention.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109602"},"PeriodicalIF":9.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating drivers of free-living diazotroph activity in paddy soils across China","authors":"Xiaomin Wang ,&nbsp;Min Wu ,&nbsp;Zhijun Wei ,&nbsp;Christina Hazard ,&nbsp;Graeme W. Nicol ,&nbsp;Huicheng Zhao ,&nbsp;Binbin Liu ,&nbsp;Jinbo Zhang ,&nbsp;Jun Shan ,&nbsp;Xiaoyuan Yan","doi":"10.1016/j.soilbio.2024.109601","DOIUrl":"10.1016/j.soilbio.2024.109601","url":null,"abstract":"<div><div>Microbially mediated N fixation is widespread in rice paddy ecosystems and crucial in maintaining soil fertility. However, our understanding of the factors determining the distribution of free-living diazotrophic microorganisms that perform this process in paddy fields is limited. This study investigated the spatial distribution and factors influencing presence and potential activity of free-living microorganisms capable of N₂ fixation in addition to dissimilatory nitrate reduction to ammonium (DNRA), anaerobic ammonium oxidation (anammox), and denitrification in 50 paddy soils across China. Using ¹⁵N isotope tracing in laboratory incubations and microbial community analysis via metagenomics, we demonstrate that paddy soils may represent a previously underappreciated hotspot for N₂ fixation with mean potential rates of 24.4 ± 17.8 nmol N g⁻¹ h⁻¹, 10-fold higher than DNRA (2.55 ± 0.4 nmol N g⁻¹ h⁻¹), and could counterbalance a portion of N₂ losses through anammox and denitrification (9.24 ± 1.1 nmol N g⁻¹ h⁻¹). Site longitude and organic carbon (C) concentrations, as well as the diazotrophic community composition, were the dominant abiotic and biotic factors accounting for regional variations in potential N₂ fixation rates. The N₂ metabolic pathways predicted from the metagenome-assembled genomes (MAGs) revealed significant co-occurrence of the diazotroph marker gene <em>nifH</em> with denitrification-associated genes (<em>nirS/K</em> and <em>nosZ</em>) and organic C oxidation-related genes (<em>yiaY</em> and <em>galM</em>). Furthermore, enzymes involved in organic C oxidation, particularly glycoside hydrolases and glycosyltransferases, were not only phenotypically correlated with free-living N₂ fixation rates but were also identified in <em>nifH</em>-containing MAGs, indicating the heterotrophic capabilities of diazotrophs in paddy soils. Collectively, our results underscore the substantial contribution of free-living N₂ fixation to soil N fertility in paddy fields, and highlight the importance of coupling organic C oxidation with nitrate reduction to enhance N₂ fixation.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109601"},"PeriodicalIF":9.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}